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Lenz's Law (H 16)


Keyword: Electromagnetic Induction

Demonstration Description:
One aluminum tube and one plexiglas tube are mounted on a vertical stand. Two apparently identical bobs are dropped through the tubes at the same time. One bob takes several seconds longer to fall through. One bob is strong magnet. As it falls through the aluminum tube it induces an electric field which in turn generates a magnetic field of its own, slowing the fall of the magnetic bob. The bobs can be reversed and they fall at the same rate. In 26-100 the TV projection system has to be used.

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